At first I was confused and felt you were talking about the Cooper \ Sheridan movie Good Sam. That movie had a fine cast also but it wasn't very good. The two stars never really clicked in that one. I haven't seen this Lemmon movies so I hope TCM shows it soon.
It still hasn't aired since you posted your comment a year ago. But when it does turn up on TCM again, I think you'll enjoy it. It's overlong in parts, but a lot of the comedy works thanks to Lemmon's efforts.